1. Field of the Invention
The present invention relates to a fuel cell system. More particularly, the present invention relates to a fuel cell system using a liquefied gas fuel, such as butane.
2. Description of the Related Art
A fuel cell is a generator that generates electrical energy by using a fuel and an oxidant gas.
Fuel cells can be broadly divided into polymer electrolyte membrane fuel cells and direct oxidation membrane fuel cells.
A system that employs polymer electrolyte membrane fuel cells includes a stack, a reformer, a fuel supply, and an oxidant gas supply. The stack includes a plurality of fuel cells consecutively arranged therein; the reformer generates a reformed gas by reforming a fuel; the fuel supply supplies the fuel to the reformer; and the oxidant gas supply supplies the oxidant gas to the stack.
When the fuel is supplied to the reformer, the reformer reforms the fuel and generates reformed gas. When the reformed gas and the oxidant gas are supplied to the stack, electrical energy is generated in the stack by an electrochemical reaction of the reformed gas and the oxidant gas.
Recently, a fuel cell system using a liquefied gas fuel that can be easily purchased at the market has been suggested.
Butane has a relatively low boiling point and can be easily liquefied with a relatively low pressure, and therefore, butane can be contained in a partially liquefied state in a fuel tank and supplied to the reformer.
However, since the fuel is stored in a partially liquefied state in the fuel tank in the fuel cell system, the fuel is vaporized by heat around the fuel tank and is then emitted.
Accordingly, the temperature of the fuel tank is decreased due to latent heat of vaporization, and when the temperature is lower than a boiling point of the fuel, the internal temperature of the fuel tank is decreased, thereby causing deterioration in vaporization characteristics of the fuel.
Therefore, the fuel tank cannot sufficiently provide fuel to the reformer since the amount of vaporized liquefied gas fuel has been reduced.